Abstract
The cytotoxicity of 13 and 22 nm aluminum oxide (Al
2
O
3
) nanoparticles was investigated in cultured human bronchoalveolar carcinoma-derived cells (A549) and compared with 20 nm CeO
2
and 40 nm TiO
2
nanoparticles as positive and negative control, respectively. Exposure to both Al
2
O
3
nanoparticles for 24 h at 10 and 25 µg mL
−1
doses significantly decreased cell viability compared with control. However, the cytotoxicity of 13 and 22 nm Al
2
O
3
nanoparticles had no difference at 5-25 µg mL
−1
dose range. The cytotoxicity of both Al
2
O
3
nanoparticles were higher than negative control TiO
2
nanoparticles but lower than positive control CeO
2
nanoparticles (TiO
2
< Al
2
O
3
< CeO
2
). A real-time single cell imaging system was employed to study the cell membrane potential change caused by Al
2
O
3
and CeO
2
nanoparticles using a membrane potential sensitive fluorescent probe DiBAC
4
(3). Exposure to the 13 nm Al
2
O
3
nanoparticles resulted in more significant depolarization than the 30 nm Al
2
O
3
particles. On the other hand, the 20 nm CeO
2
particles, the most toxic, caused less significant depolarization than both the 13 and 22 nm Al
2
O
3
. Factors such as exposure duration, surface chemistry, and other mechanisms may contribute differently between cytotoxicity and membrane depolarization.